You've signed up to receive emails. Please check your email for a welcome confirmation.

Doyle says there's a huge demand both from Syrian refugees, as well as criminals who are trying to take advantage of the situation in Syria. There are Syrians, Doyle explains, whose passports have expired as the war has dragged on.

"Those who live in the opposition areas of Syria and are not able to renew their passports have a really big problem," Doyle explains. "There are large numbers now [of] stateless Syrians — that is that their passports have gone out of date because this conflict has now gone on for 4.5 years plus and they don’t have a valid passport anymore,” he says.

In other words, there are Syrians who are carrying fake passports just because they were not able to get their passports renewed.

But then there are those who acquire fraudulent passports because of criminal activities. They sell these passports on the black market for very large sums of money. The Syrian passport is valuable for non-Syrian migrants because European countries have pledged to take in more Syrian refugees. They stand a better chance of getting into Europe if they carry a Syrian passport.

Doyle says it could even be the case that people within the Syrian government are involved in the fake passport trade.

"[They] are happy to make some money out of this and to see opponents leaving the country, getting essentially off their books. That means one less person to deal with," he says.

The cost for a fake Syrian passport, Doyle says, ranges between $200 to $3000. The more expensive ones are harder to detect, he says. They're very similar to official Syrian passports.

The cheaper ones would be flagged more easily by border authorities. But Doyle believes with the large number of migrants trying to get to Europe, many fake passports simply go unnoticed.

According to Doyle, it's not just passports that are being forged. There is a business in fake birth certificates and even university degrees, which are used to get jobs in Europe.

"There is a war economy going on in Syria that has inverted normal economic activity. Forgeries and criminality is a huge part of that," he says.